Biunseptium
Biunseptium, Bus, is the temporary name for element 217. NUCLEAR What follows is based on a first-order, liquid-drop assessment of where the outer boundary of the nuclear world is. Assume cautious values for how many neutrons a nucleus with 217 protons can bind (high neutron dripline) and how few it can have before it fissions immediately regardless of how much the structure it can develop stabilizes it (low must-fission curve). Assume, too, that anything that lasts long enough so that protons and neutrons can be treated as particles rather than collections of quarks (is causal) might be a nucleus. Under these conditions, Bus isotopes are theoretically possible between Bus 658 and Bus 970 (see "The Final Element", this wiki). Bus 658 through Bus 764 are expected to decay by beta emission if they don’t fission quickly. Above that value of A, the confident neutron dripline, drops may decay by neutron emission before they can fission. (Structural correction does not affect neutron emission.) Isotopes lighter than Bus 690 need more than twice the structural correction energy needed to prevent fission in worst-case nuclei in the A = 480 region(1). Predicting whether or not the structure a nuclear drop can develop will allow it to survive for the 10^-14 sec required for it to bind an electron and so become an atomic nucleus is not usually possible at this time. Neutron shell closures have been predicted at N = 644, and 524(2). The former may allow some nuclei in the vicinity of Bus 861; it requires only 2 MeV structural correction, but is 13% above the confident dripline. The latter may allow some nuclei in the vicinity of Bus 741; it requires 12.5 MeV of structural correction, but lies below the confident dripline. The band Bus 730 through Bbs 866 is the most probable location for Bus isotopes. Bus 689 and lighter are implausible, while Bus 867 and heavier are highly unlikely. ATOMIC Electron structure of Bus has not been studied closely, but it is likely to differ significantly from the conventional orbitals found in lower-Z nuclei. While only the innermost electrons would be qualitatively different, other electrons are likely to be quantitatively different from those in lower-Z atoms. Bus is also large enough that nuclear shape may have an effect on electron structure, which might cause different isotopes of Bus to be chemically different. (Which means it is no longer an element in the chemical sense.) Predictions of atomic or chemical properties of Bus are risky. FORMATION Ions of this element may form when material from roughly 1 km depth is ejected from a disintegrating neutron star during a merger. It is probably impossible for lighter isotopes to form in this way. REFERENCES 1. "Decay Modes and a Limit of Existence of Nuclei"; H. Koura; 4th Int. Conf. on the Chemistry and Physics of Transactinide Elements; Sept. 2011. 2. "Magic Numbers of Ultraheavy Nuclei"; V. Yu Denisov; Physics of Atomic Nuclei, v. 68, no. 7, pp 1133-1137; 2005. (12-03-19) Category:Undiscovered elements Category:Post-eka-superactinides Category:Radioactive